As is known in the art, a golfer may determine the remaining distance to the pin by referring to permanent distance markers set out along the fairway. However, these yardage markers are generally set at 50 or 100 yard increments, requiring the golfer to interpolate or estimate his exact location. Additionally, fixed yardage markers do not account for variations in pin placement on the green, which can alter the actual distance by as much as 25 yards.
A variety of attempts have been made to provide golfers with a more accurate indication of the remaining distance to the pin. Such efforts have included the use of radio transceivers. For example, U.S. Pat. No. 3,868,692 to Woodard et al. discloses a plurality of transmitters located on the greens. Each transmitter is designed to generate an RF signal of a different frequency. The golfer uses a receiver unit that displays the relative distance to each of the transmitters.
A similar system is disclosed in U.S. Pat. No. 4,136,394 to Jones et al. which teaches a system which includes a base unit mounted at or near the pin on the green and a number of remote units carried by the golfers on the course The remote units transmit rad pulses to the base unit, and the base unit responds by returning an acoustic or ultrasonic signal. The time interval between transmission of the radio pulse and the reception of the acoustic signal defines the distance to the pin. The distance is displayed by means of a readout on the remote unit.
U.S. Pat. No. 4,698,781 to Cockerell and U.S. Pat. No. 4,703,444 to Storms et al. both describe systems wherein remote stations are located on the golf course. A signal emitted by the golfer's portable unit is received by all three remote stations. The golfer's current position on the course is triangulated and transferred to a central CPU.
The central CPU stores the location of various predetermined features on the course. The CPU calculates the distance from the golfer's current position to the specified feature and relays the distance to the golfer's portable unit, where it is displayed by use of a digital readout.
Yet another approach is set forth in U.S. Pat. No. 4,088,324 to Farmer. This patent teaches the utilization of an acceleration sensor mounted in the golf club head for detecting the deceleration shock pulse generated by striking the ball. Electronic circuits mounted in the club handle convert the analog signal from the acceleration sensor to a digital signal proportional to the distance traveled by the ball and transmits the distance to a digital display mounted on the end of the club. The golfer can estimate the current or present position by subtracting the distance the ball traveled from the total length of the hole.